diff --git a/slides/cours_9.md b/slides/cours_9.md
index d11cbeae929c18713cfcaa4c86f51a26ed5c7e6c..ec88602ef021b98415f36ba372b4282299038597 100644
--- a/slides/cours_9.md
+++ b/slides/cours_9.md
@@ -327,7 +327,7 @@ int stack_pop(stack *s) {
 . . .
 
 ```C
-int stack_peek(stack *s) {
+int stack_peek(stack s) {
     return s->data[s->top];
 }
 ```